D&D 5E When is it OK to let a player substitute one skill for another?

[Don Durito]

I'm not sure what to call it, but I see this mess all the time.

• Is it OK if use Intimidate instead of Diplomacy?

To what end? To get what you want immediately? Perhaps, but the long term results will probably be different. If you intimidate someone that won't be left with a favourable impression. If you interact with them again, their attitude should be more negative.

• Can I use Acrobatics to initiate a grapple?

Acrobatics and Athletics are weird because they're partly redundant with each other, especially if you allow skills to be used with alternative ability scores. The key point here is you can't use Dex to initiate a grapple. That's specifically Strength. I would definitely not let a player roll Acrobatics as an attempt to get around rolling strength. In theory, you could roll Strength (Acrobatics) but that seems a bit weird. But allowing Dex for grappling is taking away one of the big perks of going strength based.

• I worship the god of magic. Can I roll Arcana instead of Religion?

Again for what purpose? They're the same roll so Arcana is only better if the player did not take proficiency with religion. So then the question is how does this affect what they know? I don't see why Arcana would let you know how the church of the god of magic works, or the minutae of the celestial court of that god. But sometimes they overlap. There's been a few situations where I've specifically said that more then one skill could be applied, eg Arcana or History, or Religion or Insight (in the latter case to spot a charlatan through mistakes in their knowledge or through their demeanour).

• If I scavenge some vines, is it OK to roll Survival instead of tool proficiency to make rope?

Yeah. Why not? Tool proficiencies are mostly ribbons. A tool proficiency would let you do it without survival. I'd say the tool proficiency one would probably be better quality in the long run. The way I see it: ability scores > skills > tool proficiencies.

If a tool proficiency was going to be particularly useful in particular campaign for some reason then I'd upgrade it to a skill. (eg. In a pirate based game Navigators Tools would probably just become the Navigation skill.)

Do you just increase the DC for using an "off" skill? Do you give the player a hard "no" when it's too preposterous? How do you go about adjudicating these sort of questions?

(Comic for illustrative purposes.)

Generally no. The DC is the DC. I would use Advantage/Disadvantage rather then adjusting the DC. But of course a different skill may be applying a very different approach that might lead to a different DC. The DC for climbing a wall to break into a house will not necessarily be the same as picking the lock on the front door.

I don't have any issue with a hard no I rarely need to, however. Usually, it's a case of asking the player "How are you doing that?". If the player can't answer that they basically withdraw the attempt themselves. If they can, there's usually no reason to say know.

 

[prabe]

Just ask for ability checks and let the player pick the skill. That way there’s no table time wasted on the negotiation. Assume the players know what they want their characters to do and will act in good faith choosing the skill (or tool) they think is most appropriate for the task, and ask them to assume you will rule permissively.

A possible refinement to this is to grant Advantage if the character has two applicable Proficiencies. It's something I do regularly (though I don't work exactly the way you do).

 

[Charlaquin]

I believe one can get a little more out of skills, by allowing them to also guide to the tone or direction of the narrative. Just as many above have noted regarding using different social skills to obtain the same ends.

So when I DM, I am not thinking about the skills simply as - can the player add their PB here - but also in terms of what we decide is going on narratively. The nature of the leverage over the narrative the player is attempting to employ and where that may lead.

The social skills are clearest, but as others have intimated, even a difference between applying Jeweler's tools versus History might guide the game down different paths, through changing the information obtained or casting it in a different light. Both know the necklace was stolen, but perhaps the character using History knows or has excellent reason to suspect it was taken by the rightful heir, while the jeweler heard it was fenced through Neverwinter and might now be in Waterdeep.

What I guess I am saying is that as well as a simple way to decide if an attempted action succeeds or not, skills can work as narrative prompts that guide us how the story might unfold.

I prefer to let the player’s description of what’s going on narratively dictate what’s going on narratively. But to each their own.

 

[Charlaquin]

A possible refinement to this is to grant Advantage if the character has two applicable Proficiencies. It's something I do regularly (though I don't work exactly the way you do).

I prefer to be the one to grant advantage (except in the case of players spending inspiration), so that wouldn’t work for me since I leave it to the player to determine if their proficiencies are applicable.

 

[prabe]

I prefer to be the one to grant advantage (except in the case of players spending inspiration), so that wouldn’t work for me since I leave it to the player to determine if their proficiencies are applicable.

That's fair. If the players are making the determination about whether they have proficiency, giving them the ability to decide they have Advantage is ... fraught, I agree.

 

[Charlaquin]

That's fair. If the players are making the determination about whether they have proficiency, giving them the ability to decide they have Advantage is ... fraught, I agree.

It could work. I trust the players to make the determination in good faith, so it should be no issue to allow them to grant themselves advantage if they have two or more relevant proficiencies. I just prefer that advantage be something you seek through circumstantial, uhh, advantages, rather than being intrinsic to your proficiencies.

 

[prabe]

It could work. I trust the players to make the determination in good faith, so it should be no issue to allow them to grant themselves advantage if they have two or more relevant proficiencies. I just prefer that advantage be something you seek through circumstantial, uhh, advantages, rather than being intrinsic to your proficiencies.

That makes sense. I just figure that if you happen to have two proficiencies that apply, it should do you some good. Horses for courses, I suppose.

 

[iserith]

I prefer to let the player’s description of what’s going on narratively dictate what’s going on narratively. But to each their own.

Yeah. Their role in the game is to describe what they want to do. If they don't, then the DM's role becomes harder for no good reason.

 

[Umbran]

Not in the normal sense of the word 'optional'. Certainly in the extended sense, that all rules are optional.

I think also in the sense that the GM can ask themselves, "Should this PC know how to do this? If yes, then add their proficiency (or double, for expertise) bonus," and not much is going to break.

 

[iserith]

That makes sense. I just figure that if you happen to have two proficiencies that apply, it should do you some good. Horses for courses, I suppose.

What it suggests to me is that the player has two different approaches to the same goal. For example, Influence NPC (Charisma) via threats (Intimidation) or social graces (Persuasion).